The alpha-amylase activity in whole saliva of two groups of infants was investigated from birth to 5 months at monthly intervals. Foods used in infant feeding as well as height and weight were recorded at each monthly collection period. alpha-Amylase activity was found to increase rapidly from low values at birth to approximately two-thirds of adult values by 3 months. Large variation in alpha-amylase activity, either per ml of saliva or per mg of protein, was recorded. No significant relationships of alpha-amylase activity with weight, weight for height, growth rate, or presence of starch-containing foods in the diet were found. Introduction of starch-containing food before 3 months of age would likely lead to inadequate hydrolization of starch in some infants.